Grinder



May l, 1943 A. L.. EvANis 2,319,311

GRINDER4 Filed Sept. 1'?, 1941 3Sheets-Sheet 1 May l@ 1943 A L. VANS I 2,319,311

A GRINDER Filed Sept. 17, 1941 3v Sheets-Sheet 3' Patented May 18, 1943 UNITED STATES PATENT OFFICE GRTNDER Arthur L. Evans, Detroit, Mich. epplieatien september 17, 1941, serial Ne. 411,097 s Claims. (C1. 51166 This invention relates to a grinder.

Heretofore it has been customary in grinders to mount the grinding or abrasive wheel directly on the shaft of an electric motor. The shaft of an electric motor invariably is loose and has considerable play in it. Due to this looseness or play in the mounting of the motor shaft, the grinding wheel necessarily has play or looseness in it.

This play in the grinding wheel adversely affects the accuracy or precision obtainable in the grinding operation. To partially counteract the looseness in the grinding wheel it has been customary to use a Wheel made from a fine grained abrasive. e

With a loose wheel a greater grinding precision is obtainable with a ne grained than witvha coarse grinders heretofore used. This object is achieved4 by a, particular mounting for the grinding wheel so that it is free from play or looseness both axially and transversely of the axis of rotation of the wheel.

The mounting of the grinding Wheel so that it is free from play in all directions makes possible the use of a coarse grained Wheel by means of which just as accurate grinding can be obtained yas with a finer grained Wheel and yet the need for frequent dressing down of the wheel is obviated.

In the fabricating of a grinding Wheel it is practically impossible to uniformly distribute the Weight of the wheel, that is, some areas will be denser and have a higher specific gravity than other areas. Due to this variation in density, any looseness or play in the mounting of the Wheel will result in .the wheel wobbling or vibrating while rotating. Even though a grinding wheel can wobble but very slightly due to play in its mou-nting shaft, the coarser the grain of the wheel the greater the gouging and the rougher the grind resulting from the play in the wheel mounting. If the wheel is held absolutely against play in all directions, then as precise a grind is obtainable with a coarse grained Wheelvas with a ne grained wheel. It is this object which is achieved by this invention.

In the drawings:

Fig. 1 is a side elevation showing the portable grinder.

Fig. 2 is a vertical axial section through the grinding wheel and mounting therefor.

Fig. 3 is a side elevation of the grinder viewed from the left hand side of Fig. 1.

Fig. 4 is a section along the line 4-4 of Fig. 3.

Fig. 5 is a section along the line5-5 of Fig. 2.

Referring more particularly -to the drawings, the grinder comprises a frame I whichismounted upon the wheels 2 so as to be'portable from place to place in the shop where the Igrinder is used. A work support 3 is adjustably mounted on the frame I adjacent the abrasive Wheel 4. This grinder is arranged t0 grind along the flat face 5 of the grinding wheel rather than along its circumferential face.

'I'he grinding wheel comprises an abrasive Wheel or ring 6 fixed on la rigid backing plate 1 of steel or other material. The plate 1 isbacked up by another plate 8 of steel or other suitable material. The shaft upon which the wheel 4 is supported is designated 9. Y

Shaft 9 is provided adjacent Yone end with an integral flange I0. Wheel 4 and plate 8 are mounted over the stub end II of the shaft and rigidly secured thereto by bolts I2 which screw into the flange I0. The upper portion of the frame I is in the form of a housing I3 which serves as a supportfor the shaft 9. The shaft 9 is supported within the housing I3 by the thrust bearing races I4, I5 and I6. A cylindrical spacing sleeve I1 is mounted within the housing I3 and secured in place by the set screw I8 which interengages the sleeve I1 in the conical depression I9. Set screw I8 effectively 'locks sleeve I1 against any axial movement in the housing I3. The right-hand end of the shaft 9 is threaded as at 20 to receive the lock nut 2| and lock washer 22. A flexible coupling 23 connects shaft 9 with the shaft 24 of the motor 25. Motor 25 is secured to the frame I by bolts 26.

Shaft 9 is assembled in the housing as follows: After sleeve I1 has been locked in the housing I3 by set screw I8, the bearing race 21 is mounted against flange I0 and over shoulder 28'on shaft 9. Thrust bearing races I4 and I5 are now `placed over shaft 9 against circumferential shoulder 28. The shaft 9, with the bearings 21, I4 and I5, is now slipped into the left-hand end of housing I3 and passed through sleeve I1. Thrust bearing race I6, spacing ring 29 and bearing race 30 are now slipped over the righthand end of shaft 9 and nut 2| is turned on to the threaded end 20 of the shaft and turned down tight and then locked in place by lock washer 22. Turning of nut 2I causes the thrust bearings I4 and I5 to be held tightly between shoulder 28 on the shaft 9 and the sleeve I1. Ring 29 and thrust bearing race I5 are held tightly between the other end of the sleeve I1 and nut 2I. Thus the ends of sleeve I'I act as shoulders within housing I3 which cooperate with shoulder 28, nut 2l and the thrust bearing races to hold shaft 9 against axial movement or play. Since bearing races I4, I5 and I have a precision fit with the shaft 9, the shaft is positively held in the housing I3 against any looseness or play transversely of the axis of the shaft. The nut 2| and shoulder 28 cooperate with the sleeve II and the thrust bearing races I4, I5., I6, and ring 29 to positively hold the shaft 9 Aagainst any axial movement.

A U-shaped guard 3I is provided for wheel 4. Guard 3| is mounted upon rods 33 which have an adjustable sliding fit in lugs 34 of housing I3. Rods '33 are held in their adjusted position by set screws 35. Guard 3I, of course, is adjusted each time the flat face of the wheel 4 is dressed down. Housing I3 is provided with a reservoir 3B for oil or other lubricating fluid. Ring 31 fits loosely over shaft 9 and is suspended in the oil in reservoir 36. As the shaft 9 rotates, ring 37 also rotates and carries the oil from the reservoir `36 on to the shaft 9 and its supporting bearing races. Ring 31 is held inposition on the shaft 9 bythe oppositely tapered surfaces 40 and 4I.

I claim: v 1.- In a grinding machine, a shaft adapted for supporting a grinding wheel, a shoulder on said shaft, a housing in which the shaft is mounted, a removable sleeve in said housing, means for positively securing said sleeve in place within and to the housing, thrust antifriction bearing races positioned on opposite sides of the sleeve in the housing for supporting th'e shaft in the housing free from play transversely of the shaft, and means carriedV bythe shaft for placing the shaft in tension whereby one of the-'bearing races CII is clamped between the shoulder on the shaft and one end of the sleeve in the housing and the other race is clamped between the said means and the other end of the sleeve in the housing to hold the shaft against axial play.

2. In a grinding machine, a shaft adapted for supporting a grinding wheel, a circumferential flange on said shaft, a housing in which the shaft is mounted, a removable sleeve in said housing positioned over said shaft and having substantially the same external diameter as the internal 'diameter of the housing, means for interengaging said sleeve and housing to lock said sleeve in place within and to the housing, thrust antifriction bearing races positioned on opposite sides of the sleeve in the housing for supporting the shaft in the housing free from play transversely of the shaft, and means carried by the shaft for placing the shaft in tension whereby one of the bearing races is clamped between the circumffer'ential flange on the shaft and one end of the sleeve in 'the housing vand the other race is clamped between the .said means and the other end of the 'sleeve inthe housing to hold the shaft against axial play.

3'. In va grinding machine, `a shaft adapted for supporting a grinding wheel, a, circumferential flange on said shaft, a housing' in which the shaft is mounted, a removable sleeve in `said housing positioned over Said shaft and vhaving substantially the same external `diarr'ieter as the internal diameter of the housing', means between said sleeve and housing 'for interlocking said sle'e've in place 'within the housing and against longitudinal movement, thrust antifriction bearing races positioned on opposite-'sides of the sleeve in the housing for supporting the shaft in the housing 'free from play transversely of the shaft, a nut screwed on the shaft for placing 'the shaft in tension whereby one of the bearing races is clamped between the circumferential flange on the shaft and one end of the sleeve in the housing and Vthe other race is clamped between vthe said `nut and the other end of the sleeve in the housing t'o hold the shaft against axial play.

ARTHUR L. EVANS. 

